The present invention relates generally to scales and data gathering systems including scales which are installed in point of sale checkout counters for determining product information including the weights of products presented for purchase at the counters and, more particularly, to a scale calibrating/zeroing system which is incorporated into a scale or data gathering system for access through the upper surface thereof such that a scale can be periodically calibrated and zeroed as necessary to maintain its accuracy without removal of the scale or data gathering system from the checkout counter.
Supermarket checkout counters commonly include optical scanners mounted therein for optically scanning bar code lables on products to be purchased as the products are moved over scanning windows in the top surfaces of the scanners. The scanners read and convert the bar code lables into product identification and pricing information which is used for the sale and other merchandising purposes, such as inventory control. Since many products sold in supermarkets, for example produce, are sold by weight, oftentimes weighing scales are also positioned adjacent the checkout counters. The weighing scales can be manually operable such that sales clerks weigh products and then enter the resulting prices on associated registers. Alternately, the weighing scales can be partially or fully automated such that the weights and corresponding price information are directly passed to the registers.
One example of an automated data gathering system is disclosed in U.S. Pat. No. 4,656,344, wherein a scale and an optical scanner are not only directly interconnected to an associated register but also are integrated into a single unit which fits within the checkout counter. While this integrated scale/scanner system offers advantages over the prior separated component systems in terms of convenience and space savings, still there are disadvantages and inconveniences associated with the integrated system.
For example, by making the scale and scanner a single integrated unit, the system is heavy and difficult to install and/or remove from a receiving checkout counter. While access panels can be provided in the checkout counter, if they are not, the problem is aggravated since the system otherwise must be removed from the checkout counter each time the scale is to be repaired or calibrated and then the system must be reinstalled. Further, the top surface of the system is slotted making it difficult to slide packages thereover and resulting in the collection of debris. Such debris can interfere with the passage of scanning light and also change the scale zero. If rezeroing is required, the top plate of the system must be removed or the power recycled, both operations being time consuming and a nuisance to the operator.
Of course, scales alone which may be installed into a checkout counter and other improved data gathering systems, such as the data gathering system disclosed herein which is the subject of U.S. Pat. Application entitled Point-of-Sale Data Gathering System Ser. No. 328,272, may be sufficiently light in weight or structured such that they can be more easily handled to overcome the installation and removal problem. However, movement of a scale or data gathering system may affect calibration, increases the possibility of damage due to handling and, in any event, requires additional service time and therefore expense such that even for these scales and improved systems, repeated movement for routine maintenance is undesirable and to be avoided.
Accordingly, there is a need for a scale calibration and zeroing arrangement which permits the scale or scale incorporating data gathering system to remain in place within a checkout counter while the scale is calibrated and/or zeroed. Preferably, zeroing of the scale can be quickly performed without interrupting its power supply or partially disassembling the system.